Control apparatus



F. H. GULLIKSEN CONTROL APPARATUS Filed Sept. 30, 1938 April 8, 1941. 2,237,665

WITNESSES: INVENTOR ATTORNE Patented Apr. 8, 1941 e Q OFFICE CONTROL APPARATUS Finn H. Gulliksen, Pittsburgh, Pa., assignor to Westinghouse Electric & Manufacturing Company, East Pittsburgh, Pa., a corporation of Pennsylvania Application September 30, 1938, Serial No. 232,651

1 Claim. (01. 250-415) My invention relates to control apparatus and limits, as for example, ina sewage disposal plant,

has particular relation to apparatus for profor controlling traflic in response to vehicle actuducing extended operation of translating means ation and for other similar applications. in response to energy impulses of short dura- According to my invention the actuating imtion. pulses are impressed On one or the'other of a It is often necessary to provide control appair of discharge valves of the arc'like type paratus which causes a system to operate sucsupplied from a direct current source. The valve cessively in one sense and the opposite sense for on which an impulse is impressed is rendered extended intervals of time in response to succonductive and remains conductive until an imcessive impulses persisting for short intervals of pulse is impressed on the other valve rendering time. Extensive use for such control apparatus it conductive. The two valves are so interconis found for example in sewage disposal plants nected that when the non-conductive valve is in which it is important that the level of the rendered conductive, it extinguishes the origsluclge be maintained between two well defined inally conductive valve.

limits. When the sludge level rises above the The novel features that I consider characterupper limit, a valve is opened and a pump is set istic of my invention are set forth with parinto operation to lower the level and when the tic-ularity in the appended claim. The invention sludge level falls below the lower limit, the. conitself, however, both as to its organization and verse ope-ration takes place. Control apparatus its method of operation, together with additional of the same type may also with advantage be objects and advantages thereof will best be used in vehicle actuable trafiic regulating sysunderstood from the following description of a terns. In such a case an impulse produced by specific embodiment when read in connection a vehicle moving in one of a pair of intersecting with the accompanying drawing, in which the highways causes a right of way signal to be dissingle figure is a diagrammatic view showing an placed for the highway and a stop signal for the embodiment of my invention.

other intersecting highway, and a vehicle sub- In the drawing, my invention is shown as apsequently moving in the latter highway and proplied to the regulation of the level of a liquid.

ducing a corresponding impulse causes the right In such a case the liquid level is controlled by of way to be transferred from the former higha valve (no-t shown), the opening of which is' way to the latter highway, and the stop signal ,3? varied by a reversible direct current motor I. to be transferred from the latter highway to the The motor is supplied from a direct current former highway. Control apparatus for prosource 3 through the contacts of one or the other ducing the desired operation constructed and of a. pair of relays 5 and For one direction operated in accordance with the prior art of H of rotation of the motor I, current is supplied which I am aware is relatively complex and, in a circuit extending from the positive line contherefore, is expensive and requires considerable ductor 9 of the source 3 through a conductor servicing. II, a conductor I3, the lower movable contactor It is, accordingly, an object of my invention to I5 of one of the relays 5, a conductor I1, the provide control apparatus of simple and tractable armature I9 of the motor I, a conductor 2|, the structure for use with a translating system which upper movable contactor 23 of the same relay,

shall produce successive operation of the transa conductor 25 to the negative line conductor lating system in one sense and the opposite sense 21. Current of the opposite polarity is supplied in response to successive short energy impulses. to the motor I in a circuit extending from the 'Another object of my invention is to provide positive line conductor 9 through the conductor control apparatus for a translating system which, I I, the upper movable contactor 29 of the other in response to an impulse shall produce operarelay I, a conductor 3|, the conductor 2|, the tion of the system in one sense and in response armature I9 of the motor, the conductor II, the to another impulse shall produce operation of lower movable contactor 33 of the relay, the conthe system in the second sense, the operation in duo-tor 25 to the negative line conductor 21.

the first sense continuing until after the opera- The exciting coils 35 and 31 of the relays 5 tion in the second sense has been initiated. and 1, respectively, are in the anode circuits of More concisely stated, it is an object of my electric discharge devices 39 and 4|, respectively. invention to provide simple and inexpensive ap- Each of the discharge devices is of the arc-like paratus particularly adapted for use in maintaintype and comprises an anode 43, a hot cathode ing a level of a liquid between two well defined and a control electrode 41 and an ionizing medium such as is produced by a noble gas or by mercury vapor. The discharge devices are supplied from the direct current source 3. The circuit for the left-hand relay coil 35 extends from the positive line conductor 9 of the source through the exciting coil 35, the anode 43 and the cathode 45 of the left-hand discharge device 39, a'conductor 49 to the negative line conductor 21. The circuit for the other coil 31 is similar. The anodes 43 of the discharge devices 39 and 4| are interconnected by a capacitor which functions to render a conductive discharge device non-conductive when the other discharge device is rendered conductive.

The discharge devices 39' and 4| are controlled from photo-sensitive devices 53 and 55, respectively. The cathode 51 of each of the photosensitive devices 53 and 55 is connected directly to the control electrode 41 of the corresponding chscharge device. The anodes 59 of the photosensitive devices are connected together and their common junction point 6| is connected to the positive terminal 83 of a voltage divider 65, the adjustable tap 61 of which is connected to the common junction point 69 of the cathodes 45 of the discharge devices 39 and 4|. The negative terminal H of the voltage devider 65 is con.- nected through suitable 'grid resistors 13 and 75, respectively, to the control electrodes 41 of the discharge devices 33 and 4| and, therefore, a negative bias potential, when the photo-sensitive devices 53 and 55 are unexcited, is impressed in the control circuits of the discharge devices through the voltage divider 65.

The conductivity of the photo-sensitive devices 53 and 55 is controlled by radiant energy sources 7'! and 19, respectively. The sources may be of any suitable type and may project visible or invisible radiations in accordance with the requirements of the apparatus. The radiant energy beams from the sources 11 and 19 are intercepted by an opaque object 8| which, in the present case, is a float which rises and falls in accordance with the level of the liquid to be regulated.

For the purpose of explaining the operation, let us assume that when the circuit is first closed the float 8| blocks the radiant energy impinging on both photo-sensitive devices 53 and 55. In such a case the corresponding discharge devices 39 and 4| are initially non-conductive. Let us now assume that the level of the liquid is rising so that the float 8| is moved upward. In such a case the float eventually rises above the lower radiant energy beam, permitting the lower photosensitive device 53 to be rendered conductive. The bias impressed in the control circuit of the left-hand electric discharge device 39 to which the lower photo-sensitive device 53 is connected is counteracted by the current flow through the photo-sensitive device 53 and the left-hand discharge device 39 is rendered conductive. The associated relay 5 is then energized and causes the motor I to rotate the valve in a direction such as to lower the level of the liquid. 1 The float 8| now drops so that it blocks the radiant energy impinging on the lower photo-sensitive device. However, this has no effect on the left-hand discharge device 39' and its associated relay 5 since the anode-cathode circuit of the former is supplied from a direct current source and the discharge is maintained in spite of the variation in control potential. The current flow through the left-hand discharge device 39, however, causes the capacitor 5| to charge with its left-hand plate 83 negative and its right-hand plate 85 positive.

The float 8| continues to fall with the liquid until it has dropped to a level permitting radiant energy to impinge on the upper photo-sensitive device 55. In such a case the associated righthand discharge device 4| is rendered conductive and the right-hand relay 1 becomes energized. At the same time the positive plate 85 of the capacitor 5| is connected through the right-hand discharge device 4|, which has a relatively small arc drop, to the cathode 45 of the left-hand discharge device 33. Since the anode 43 of the lefthand discharge device 39 is connected "to the negative plate 83 of the capacitor 5| the negative potential of the capacitor is now impressed across the left-hand device 39 and the latter is rendered non-conductive. The left-hand relay 5, therefore, drops out and the motor now rotates in a direction such as to close the valve, and to permit the liquid level to rise. Again the fact that the radiant energy from the upper source to the upper photo-sensitive device 55 is interrupted is of no consequence since the right-hand discharge device is supplied from a direct current source. On the other hand, the capacitor 5| is now charged with its right-hand plate 85 negative and its left-hand plate 83 positive. The level of the liquid now rises until the lower photo-sensitive device 53 is rendered conductive and the converse of the above described process is repeated.

Although I have shown and described certain specific embodiments of my invention, 1 am fully aware that many modifications thereof are possible. My invention, therefore, is not to be restricted except insofar as is necessitated by the prior art and by the spirit of the appended claim.

I claim as my invention:

In combination with a source of uni-directional current and a load to be supplied thereby, a pair of grid-controlled electrical discharge devices each having an anode, a cathode and a control electrode, a common connection to the cathodes of said two discharge devices joining them to the negative terminal of said source, a separate connection embodying one of said operating coils from the anode of each said discharge device to the positive terminal of said source, a capacitor having its terminals respectively connected to the respective anodes of said discharge devices, one of said circuit interrupting means being adapted to connect said load to said source with one polarity when its associated operating coil is energized and the other said circuit interrupting means being adapted to connect said load to said source with the opposite polarity when its associated operating coil is energized, photosensitive means connected to one of said discharge devices to render the latter conductive when itis illuminated, a second photo-sensitive means connected to the control electrode of the other of said discharge devices to render the latter condutcive when said second photo-sensitive means is illuminated, and float actuated means for so controlling the illumination incident upon said two photo-sensitive devices that they are never simultaneously illuminated.

FINN H. GULLIKSEN. 

